This invention relates generally to terminals for terminating wires and more particularly terminals which terminate wires by being crimped thereon.
In the prior art there are many different crimpable terminals. Almost all of these prior art crimp type terminals employ a metal barrel into which the end of a wire is laid and then the metal barrel is crimped around the wire, making both an electrical connection and a mechanical connection therewith. In most cases the connections do not require solder; the force of the crimping itself creates an extrusion of the wire therein to provide good electrical and mechanical connection.
In one of the several different types of crimps in common use today the barrel is crimped so that the cross-sectional configuration thereof is generally cardioid in shape; although somewhat flatter and is commonly referred to as an "F" type crimp. Another type crimp is circular in nature and is commonly referred to as an "O" type crimp. A third type crimp is generally flat in nature wherein the barrel is forced down upon the wire between two surfaces which are flat and substantially parallel with each other.
Many prior art crimp type terminals have serrations in the barrel which usually run circumferentially around the barrel, although other configurations are sometimes employed. Such terminals usually have other portions attached thereto, such as a ring tongue portion or a spade portion for securing to a terminal lug or bolt, for example. A problem sometimes arises when large gauge wires are to be crimped, in that a relatively large mass of metal, i.e., a heavy gauge material, is required for the barrel to properly retain the large gauge wire. However, such heavy gauge metal frequently is not required with the spade or ring tongue portion. Accordingly, considerably more material is utilized in the manufacturing of such terminals than is really needed. When millions of terminals are being manufactured, the excess material used in each terminal accumulates to a large amount and represents a substantial amount of expense. On the other hand, if the thickness of the barrel portion is reduced to the thickness required for the ring tongue portion of the terminal, then the heavy gauge wire will not be properly retained within the crimped barrel.
Another common problem is the range of wire sizes with which any given barrel size can be used. In most terminals of this type only a range of two or three gauges of wire can be crimped within a given barrel. If the barrel is too small, the wire is not properly retained, and if the barrel is too large, then the wire does not fill up a sufficient amount of the barrel cavity after crimping to provide good electrical contact and mechanical tensile strength. More specifically, in the case where the wire is too large for the barrel, the barrel tends to relax excessively, thereby reducing the effectiveness of the electrical contact as well as reducing the tensile strength.
Also, in the case of a single barrel terminal air and the corrosive elements it contains can more freely enter the crimped barrel and cause corrosive effects which decrease the effectiveness of the electrical connection and sometimes the tensile strength.
In cases where serrations are used in single thickness barrels the grooves between the ridges or serrations cannot become much wider as the crimping occurs, which places limitations on the effectiveness of the crimp. More specifically, the ridges or serrations cannot spread apart as crimping occurs because they are an integral part of the barrel. The wire, however, extrudes significantly in a longitudinal direction during crimping. Thus, there is a tendency for the edges or walls of the serrations to be crumbled by the extruding wire during crimping so that the metal of the wire is not forced down into the grooves between the serrations as completely as is desired.
While there is some spreading of the serrations of a single walled barrel during crimping, and then a springing back of said serrations towards each other after the crimping force is removed to grip the copper which has been extruded in between the serrations, such effect is deteriorated by the afore-mentioned crumbling of the edges and walls of the serrations in a single thickness barrel.
Still another problem encountered in currently used crimp type terminals is the relatively large crimping force required in order to extrude large gauge wires so that good electrical and mechanical connection is made therein. In many cases this relatively large crimping force precludes the crimping of said barrel which have had a plastic sleeve placed thereover. In such cases, crimping must be done before the plastic sleeve is placed over the terminal, which requires an extra manufacturing step.